Landslide susceptibility assessment in the Upper Orcia Valley (Southern Tuscany, Italy) through conditional analysis: a contribution to the unbiased selection of causal factors

Abstract. In this work the conditional multivariate analysis was applied to evaluate landslide susceptibility in the Upper Orcia River Basin (Tuscany, Italy), where widespread denudation processes and agricultural practices have a mutual impact. We introduced an unbiased procedure for causal factor selection based on some intuitive statistical indices. This procedure is aimed at detecting among different potential factors the most discriminant ones in a given study area. Moreover, this step avoids generating too small and statistically insignificant spatial units by intersecting the factor maps. Finally, a validation procedure was applied based on the partition of the landslide inventory from multi-temporal aerial photo interpretation. Although encompassing some sources of uncertainties, the applied susceptibility assessment method provided a satisfactory and unbiased prediction for the Upper Orcia Valley. The results confirmed the efficiency of the selection procedure, as an unbiased step of the landslide susceptibility evaluation. Furthermore, we achieved the purpose of presenting a conceptually simple but, at the same time, effective statistical procedure for susceptibility analysis to be used as well by decision makers in land management

Dendrochronological and geomorphological investigations to assess water erosion and mass wasting processes in the Apennines of Southern Tuscany (Italy)

The Tyrrhenian side of the Central Apennines is located in a lively geological context, in which uplift/denudation dynamics played a key role in landscape evolution. Intense water erosion and gravitational processes led to the development of spectacular badlands on the widespread clayey hillslopes. The Crete d'Arbia badlands (as part of the Crete Senesi of Southern Tuscany) represent one of the most beautiful examples of these landforms developed on Pliocene clays. On the other hand, these rapidly evolving landforms endanger the artistic heritage of the area, as with the Monte Oliveto Maggiore Abbey that was constructed on the top of a badland hillslope and confers additional value to the landscape.In the perspective of monitoring and reconstructing some significant phases of the relief evolution of this area an integrated approach has been used, which is based on dendrogeomorphology and geomorphological monitoring techniques. In particular, the correspondence between the data from dendrogeomorphological indicators and the measured denudation rates on badland hillslopes was tested. The sampling for dendrogeomorphological analysis has been performed in two stages on 45 trees of the Pinus pinea L. species, on hillslopes affected by soil creep and shallow landslides, in order to identify annual ring growth anomalies, compression wood and roots exposure. Trees' local behaviour is not homogeneous but some common trends have been detected on the basis of the anomaly index and compression wood. Since 1993 several monitoring stations at badland denudation "hot spots" have been equipped with erosion pins; quantitative data from monitoring stations, compared to pluviometric series, indicated critical phases of denudation that were supported by dendrochronological data. The integrated approach between dendrogeomorphology and geomorphological monitoring techniques allowed calibration of both tools in order to extend the analysis in the period preceding the field measurements. This kind of approach, capable of implementation in many contexts, could be particularly helpful in order to forecast the relief evolutionary trend

Gully erosion in central Italy: denudation rate estimation and morphoevolution of Calanchi and Biancane badlands

Resumen del trabajo presentado al IV International Symposium on Gully Erosion, celebrado en la Universidad Pública de Navarra del 17 al 19 de septiembre de 2007.Long lasting geomorphological researches (Ciccaci et al., 1981, 1986, 2003; Del Monte et al., 2006) allowed the evaluation of denudation rates in some of the major catchments of Central Italy. It was observed a noticeable spatial variability of the denudation index (Tu) values (Ciccaci et al., 1981, 1986) and field monitoring suggested that gully erosion at badlands is likely to afford the major contribution to overall denudation at catchments scale. This paper summarizes the original results of the last three years of researches, performed on Tevere, Paglia and Ombrone basins. By thickening field monitoring, it was evidenced as well a variability of denudation rates among sharp- and rounded-edged badlands (calanchi and biancane), according to their different morphoevolution

Note illustrative della Carta geomorfologica d'Italia alla scala 1:50.000, Foglio n. 389 Anagni.

Lo studio si riferisce ad un’estesa area del Lazio meridionale (oltre 600 km2), territorio di pertinenza del Foglio 389 “Anagni” (scala 1:50.000) oggetto del Progetto CARG. Nella presente nota vengono sinteticamente illustrati i fondamentali lineamenti geomorfologici, la cui analisi ed interpretazione è finalizzata, oltre che alla ricostruzione di un primo schema morfo-evolutivo dell’area, soprattutto alla definizione degli aspetti di interesse applicativo. Aspetti di primaria importanza per la progettazione, l'organizzazione e la gestione del territorio, in quanto rappresentano condizionamenti di vario grado all’utilizzo del territorio stesso. In particolare, il lavoro mira ad evidenziare gli elementi morfodinamici cui sono associate le situazioni di più elevata "pericolosità geomorfologica": movimenti in massa e processi fluvio-torrentizi. Lo studio si riferisce ad un’estesa area del Lazio meridionale (oltre 600 km2), territorio di pertinenza del Foglio 389 “Anagni” (scala 1:50.000) oggetto del Progetto CARG. Nella presente nota vengono sinteticamente illustrati i fondamentali lineamenti geomorfologici, la cui analisi ed interpretazione è finalizzata, oltre che alla ricostruzione di un primo schema morfo-evolutivo dell’area, soprattutto alla definizione degli aspetti di interesse applicativo. Aspetti di primaria importanza per la progettazione, l'organizzazione e la gestione del territorio, in quanto rappresentano condizionamenti di vario grado all’utilizzo del territorio stesso. In particolare, il lavoro mira ad evidenziare gli aspetti morfodinamici cui sono associate le situazioni di più elevata "pericolosità geomorfologica": movimenti in massa e processi fluvio-torrentizi